Maidenhead Locator System coordinates

[fcatt]

🚀 feature request

Description

Maidenhead Locator System is used by radioamateurs to indicate geographical coordinates in a concise way, even in bad transmission conditions. This system is greatly adopted by the community all over the World.
The coding uses alternating pairs of letters and digits to encode longitude and latitude. With 6 characters the precisions is ≈ 10 km, for more precise location (extended locator), it il possible to add 2 additional digits.
See en.wikipedia.org/wiki/Maidenhead_Locator_System

Describe the solution you'd like

In the coordinates dropdown panel from the map context menu, displaying coordinates in the Maidenhead Locator System format alongside others coordinates formats.

Describe alternatives you've considered

There are two standalone Android apps on the Playstore (no F-Droid or direct APK download) from the same developper and unknown licence: com.us1pm.gridsquarelocator (current/last known device location only, no map) and com.us1pm.gridzone (uses a Google Maps background).

[vshcherb]

Similar priniciple to pluscodes (https://maps.google.com/pluscodes/#:~:text=What%20are%20Plus%20Codes%3F,displayed%20as%20numbers%20and%20letters.) and OSM short url

[onitake]

I tried to implement this in #18436 but couldn't manage to build OsmAnd locally, so it's completely untested.